1. Field of the Invention
The present invention relates generally to apparatus for heat sealing a thermally-sensitive material to an underlying substrate material, and more particularly to apparatus for closing bags containing sterilized surgical instruments and the like.
2. Description of the Prior Art
In some medical applications, sterilized surgical instruments and the like are often stored in protective bags having a sheet of mylar perimetically bonded to an underlying sheet of treated paper. The treated paper is permeable to ethylene oxide, which gas may be used to sterilize the instruments after the package has been sealed.
However, many surgical instruments are reusable, and must be repackaged after treatment in an autoclave. The packaging material may be supplied in the form of a rolled tube, the open ends of which must be sealed. While many types of heat sealing apparatus have been developed, the prior art type employing one or more heated rollers has been plagued with the problem of at least one of the rollers propagating an air bubble in advance of the roller. The presence of this bubble may impede or impair the integrity of the seal being formed. While in many packaging applications, such a faulty seal might not be critical, it is important to maintain the sealing integrity of a package containing sterilized surgical instruments or supplies.